1. Field of the Invention
The present invention relates to an apparatus and a method for manufacturing an implant using an amorphous alloy, and more particularly to an apparatus and a method for manufacturing an implant having a screw thread on an inner peripheral surface or an outer peripheral surface thereof by die-casting or pressing an amorphous alloy.
2. Description of the Related Art
In recent years, various materials are being developed due to rapid development of the amorphous alloy material technology.
The amorphous alloy is known to be suitable for biomaterials due to its high hardness, and excellent wear-resistant property and corrosion-resistant property.
Die casting has been developed as a process for forming an amorphous alloy, which corresponds to a method of heating an amorphous alloy, melting the amorphous alloy at a high temperature into a liquid state, injecting the amorphous alloy into a mold, and coagulating the amorphous alloy to form the amorphous alloy.
In the die casting using an amorphous alloy, an atmosphere needs to be controlled in the melting and forming step according to the characteristics of the amorphous material.
That is, an inert gas atmosphere such as argon or a vacuum atmosphere needs to be created.
Thus, in order to form the amorphous alloy through die casting, a separate atmosphere chamber for a melting and forming process is required to satisfy the condition and vertical die casting equipment is applied to stably realize the atmosphere chamber.
However, the vertical die casting apparatus is large-sized and high as compared with its capacity, increasing construction costs.
Further, since an ingot needs to be heated up to approximately 1000 degrees Celsius to be re-melted into a liquid state due to the characteristics of die casting, the apparatus becomes larger and the number of processes increases, increasing process cycle time.
Further, the amorphous alloy is rarely plastically deformed while a mechanical load is applied to the amorphous alloy at room temperature, but behaves resiliently as a whole.
Thus, since a thread machining technology (thread rolling or tapping) utilized in machining of a screw thread of a commercial material (iron, aluminum, and the like) is accompanied by plastic deformation of a surface of the screw thread, it is difficult to apply thread rolling or tapping which is a general thread machining technology to an amorphous alloy which is rarely plastically deformed to form a screw thread.
If a screw thread is formed in an amorphous alloy through thread rolling or tapping, a material or a tool may be damaged, resulting in a failure of the machining.
Meanwhile, a metal implant material used in a human body needs to be a stable material which is not electrically corroded in a linger liquid, and is preferably a material having a high hardness and a high strength by which the material can endure repeated frictions. Mainly, a titanium (Ti) alloy or a Co—Cr based alloy is widely used as the metal implant material.
The titanium (Ta) alloy or the Co—Cr based alloy has excellent mechanical/electrical characteristics, but has a difficulty in being applied to a forming process such as die casting due to its high melting point. Thus, the titanium (Ta) alloy or the Co—Cr based alloy is formed through three-dimensional machining.
However, since the material has excellent mechanical characteristics, it cannot be easily machined. Thus, when a complex three-dimensional shape is to be manufactured, productivity lowers and costs become higher.
It is known that an amorphous alloy such as a Zr—Ti based alloy or a Pd based alloy can be applied to a human body.
Generally, a screw thread is formed on inner and outer peripheral surfaces of a dental or surgical implant, but the method according to the related art has the following disadvantages.
Since it is not easy to machine a screw thread on inner and outer peripheral surfaces of an implant due to a high strength and a high hardness of a titanium (Ti) alloy or a Co—Cr based alloy itself, the price of the implant increases.
Further, when an amorphous alloy is used, a screw thread cannot be formed through thread rolling or tapping due to characteristics of the amorphous alloy, so die casting should be applied. In this case, since it is difficult to design a mold, for example, through setting of a gate such as injection of a molten metal is difficult, it is difficult to secure a surface quality of a screw thread, an apparatus for die casting is high, and it is necessary to re-melt an ingot into a liquid state at a high temperature before the ingot is re-melted, a life span of the mold is significantly shortened and a process cycle time becomes longer.